Plane on a Conveyor Belt
 

Don't know if anyone has been watching mythbusters lately, but they're going to test the myth of a plane trying to take off on a conveyor belt tomorrow night at 9pm est.

http://mythbusters-wiki.discovery.co...otos%21?t=anon

Oye, this topic is everywhere I look!!!! I don't have cable/dish anymore though:( I love that show

Twenty bucks says the plane propels itself off the conveyor belt.

test 1: model airplane on treadmill and it propelled forward
test 2: model airplane on large sheet of some material being pulled opposite direction (make shift conveyor) and airplane took off
test 3: experimental on 2000' strip of burlap or whatever it was being pulled by truck in opposite direction (make shift conveyor) airplane took off.


worth mentioning: quote from experimental pilot with ten years experience when asked what he thought would happen "I think im going to just sit here like a brick"

But the thing is that he didn't 'sit there like a brick'. The aircraft accelerated from its original position down the 'belt' and reached flying speed. All I saw being demonstrated was that the plane had enough thrust to overcome the rearward 'belt' movement and then move forward fast enough to reach flying speed.

This subject is being debated on numerous aviation forums right now with widely divergent views.

For me, the idea was pretty simple. If sufficient airflow over the wing wasn't there, then the plane wasn't going to fly. With no movement of the plane and therefore no airflow, how was this thing supposed to lift off?

but see the test is flawed than... the question is whether the plane would fly off if it and the belt were going the SAME speed... obvious the plane had excess thrust or had faster acceleration than the belt did.

i dont think the first two tests work either because its a trust/weight ratio.. that little plane was like a rocket...

but as im writing this and remembering the episode, i'm starting to think im a re re and am just going to shut up now :D

This is impossible to achieve. the ground has nothing to do with being propelled by thrust. The only way the ground would matter is if was stuck in mud or tied down, something actually holding it down. I can't believe they actually made an episode about this. This isn't some complicated myth that has to be physically tested to be proven. It's an obvious answer.

http://boortz.com/more/video/mythbus...eyor_belt.html

Here it is....:)

Dumb....the prop provides forward thrust, not the wheels like a car would...Doesn't matter how fast the conveyor is moving or in what direction.

That's hilarious!

Also, it's good to see the Mythbusters (finally) take on the conveyor belt controversy. I know they got pinged more than a few times based on this thread back in 2005:

http://www.airlinepilotforums.com/showthread.php?t=1762

I saw that episode and was really disappointed. Aerodynamics 101 would give you the answer... Nothing to bust

you are right, there is nothing to bust, however there are a lot of winged (military and civilian) aviators out there that think the plane should not take off....there was a huge thread about this topic well prior to mythbusters taking it on, on the website airwarriors.com (primarily a naval aviation site) and about half the people in the thread thought the plane wouldn't fly. Its sad really.....

Buster
 

This whole airplane on a conveyor belt silliness brings back a memory I have from early childhood. There was this one kid named Buster that was not so very bright. I used to wonder did Buster's his parents name him that, or did someone else because this kid was truly not very swift. One day a kid poses the question to Buster, how can a fly take off from an armrest of one seat in an airliner and then fly faster than the airliner to get to the seat a little farther ahead. Poor Buster could not get his head around this riddle no matter how hard he tried. His mind was fixed on the fact that the groundspeed of the fly had to be faster than the airplane's for it to move ahead of the airplane. We tried to inform him that the air inside the airplane moves as fast as the airplane and that even sitting still the fly was going 500 mph or so, but to no avail he was fixed on how could a fly go faster than an airliner. Poor Buster pondered this dilemma for hours and finally gave up. Funny the kids you grew up with, I think they might be at Airliners dot net arguing over the airplane on a conveyor belt.

I don't get the success- other than a safe takeoff- the plane didn't stay in one place over the ground while the conveyor zipped off in the other direction- it flew because it had airspeed, same as always- it wasn't like a zero length launch or anything interesting.

by the way- that's a good way to check your taildragger for toe-in or toe out- get a stip of paper or material wider than your gear and 100' long- PUSH the plane and see if the paper bunches up (toe in) or tear/spreads (toe out).

AMMV. So will actual ground roll.

All it did was make the wheels on the airplane go a little faster while they were still on the tarp.

Normal take-off except the wheels were spinning a lot faster...lame in my opinion. The myth should've been something like "Can the bearings on a light aircraft handle the friction produced by taking-off on a fast-moving conveyer belt?"

Ok it's 2017 and yes I saw the mythbusters episode.

What if each wheel of the plane was placed on a non electric treadmill?

That was my original thought when first ever hearing this question. If the plane doesn't get forward momentum how could it take off?

In the show it clearly moves along the conveyor belt allowing air to flow over the wings so of course it will take off.

I thought though that the conveyor belt would be fast enough to basically keep the wheels spinning in place. In that scenario it seems the plane could not take off.

Yes there are some really light planes whose thrust could maybe produce enough airflow to get it off the ground, but I'm talking about the 747 in the original question.

So, if a 747 has each wheel on a non electric treadmill, will it off?

Buster, is that you?

Yeah, saw that episode and laughed. They did one several years ago on the myth a postage stamp stuck on top of a rotor blade would make a helicopter not able to fly. I laughed harder at that one.

Here's the original question:
The original question includes the statement, "The plane moves ..." There is no assumption that the moving surface beneath the airplane keeps the airplane from moving forward relative to the ground, or relative to the air, which is the movement which will result in lift and therefore flight. In fact, there is a statement within the original question as posed to the opposite -- THE.PLANE.MOVES.

A moving surface beneath the wheels simply will not prevent the airplane from moving. All it will do is increase the speed of the turning wheels.


Your new question includes an assumption that some type of device under the wheels keeps the airplane from moving. Instead of moving forward, the airplane is held in place, and therefore will not fly.

But, no matter how fast the moving belt, and no matter how it is propelled, be it electric or non-electric, the moving surface beneath the wheels cannot keep the airplane from moving. It will only make the wheels turn faster, the same as taking off with a tailwind.

IF -- Huge IF -- IF there were some sort of device that would keep the wheels from moving relative to the ground and the surrounding air, you would be correct -- the airplane would be held in place, and therefore would not fly. That device would be called a tiedown.






.

But if the wheels turn fast enough, their motion will approach the speed of light and they will gain enormous mass, making the airplane too heavy to take off. :D

Post of the week!!! Well played sir!


Reminds me of a guy who told me he greased on every landing.
He flies the plane to within a few millimeters of the ground. The heat created between the small gap of the ground and tires would cause the tires to slightly expand and bazinga.......a grease job every time.

If they get going that fast, they go past light speed to plaid.

Everyone will be fine as long as they don't try to stop suddenly.

But they will stop suddenly, when the plaid speed causes a gigantic time reversal, and the wheels vanish because they have not yet been invented. :eek:

But only if 1.21 gigawatts was acheived in the flux capacitor

Arrgggg...

Just don't cross the streams!@!@!

(it would be bad)

If the wheels vanish, that should solve most of the problem. The treadmill should vanish about the same time, and quite likely, the airplane with it. Now, if a cheetah is nearby waiting, it becomes an issue of who's faster on foot.

That's when it gets interesting.

Only the cheetah needs to worry about being the fastest, and then only faster than the slowest occupant of the non-airplane. The rest of us only need to worry about being faster than the slowest person. Other than that, everything will sort itself out in short order.

So there you have it, Kids.
Fool around with treadmills and there will be nothing left but a fat cheetah. :p

http://numerik.blogspirit.com/media/...4288856323.jpg

Answer
 

Here's a video that explains it.


https://youtu.be/4owlyCOzDiE